Antioxidant Activity of Heterocyclic Compounds Derived from 4-(4-Acetamidophenyl)-4-oxobut-2-enoic Acid

4-(4-Acetamidophenyl)-4-oxobut-2-enoic acid 1 and / or its aza Michael adduct 2 were efficiently utilized to construct novel various heterocycles including derivatives of furanones (3a-c & 14), pyridazinones (4-6), diazepine (7), piperazine (8), oxazine (9), oxazole (10a), thiazole (10b), benzo-, [-diazin, -oxazin, -thiaz-]-ones (11a-c). Conduct (11c) with NH2-NH2..H2O in boiling ethanol and / or NH2OH.HCl in refluxing pyridine provides the corresponding hydrazone and oxime derivatives 12a and 12b, respectively. The two latter compounds showed in vitro a high potent antioxidant activity, as well as, the aza Michael adduct 2e exhibited a moderate reducing antioxidant power.